The double victories mean the American teams can finish no lower than third and fourth, ensuring the United States at least a bronze in the tournament at the iconic Horse Guards Parade. The U.S. last had two pairs in the semi-finals at the 2004 Games, where it ended up taking the gold and bronze medals.

Kessy and Ross faced a tough match against the Czech pair, which became tournament's Cinderella team after ousting heavily favored Brazilians Maria Antonelli and Talita Rocha. The U.S. and Czech teams traded several set-point serves in the first set until two unforced errors gave the Americans the win.

The American pair won 25-23, 21-18, setting up a semifinal match Tuesday against Brazilians Juliana Silva and Larissa Franca.

"We really needed to win that first set. It was huge," Kessy said. "I'm really impressed with our composure."

May-Treanor and Walsh Jennings were merciless against the reigning European champions in their match, taking just 33 minutes to win 21-13, 21-13 and reducing Menegatti to tears midway through the second set. Neither American saw her crying, but Walsh Jennings said she sensed the young player was becoming emotional as the Italians struggled to find a rhythm.

"That's by us being aggressive," May-Treanor said. "She was probably like 'I don't know what to do.' That's how you get teams in trouble."

In Tuesday's semifinal, May-Treanor and Walsh Jennings will face Xue Chen and Zhang Xi of China, who beat the Americans handily at the Moscow Grand Slam final in June. The U.S. pair say that loss prompted them to work harder to prepare for London.

"We sold the old team and we bought a new team," May-Treanor said. "Obviously, it (the June loss) is in the back of our minds, but we are a completely different team than what you saw in Moscow."

It's possible the two U.S. teams could meet each other in the finals or the bronze-medal match, but Walsh Jennings said she isn't thinking that far ahead. If it does happen, she says she plans to attack her compatriots the same way she has targeted other teams here.

"Obviously that would be amazing for our country," Walsh Jennings said of an all-American final. "But we want to crush everyone, we don't care where there from."